1. Field of the Invention
The present invention relates to train braking systems and, more particularly, to a brake monitoring system.
2. Description of the Related Art
The braking power of a train is typically the subject of strict government requirements that are designed to ensure the safe operation of trains. Currently, there is no on-board brake monitoring system for an AAR freight train. As a result, in the United States, the Federal Railroad Administration (FRA) has issued complex and burdensome rules governing train braking. For example, the FRA rules require that one hundred percent of the brakes on a train shall be effective and operative brakes prior to use or departure from certain locations. Furthermore, the train shall not move if less than 85 percent of the cars in a train have effective and operative brakes. The failure of the actual braking power of the train to exceed certain thresholds requires the train to be taken out of the service. The FRA rules also require that a train must be stopped at a qualified location every 1000 miles, more or less, depending on numerous factors, including if cars are added or removed from the train. The terminal test is burdensome as it requires the train to be sided at an approved rail yard for the test and inspection and those rail yards are often congested with other trains to be tested, trains being made up, and cars being transferred from one train to another. In addition, the terminal test is lengthy and can only be done by certain qualified personnel.
Positive Train Control (PTC) and Advanced Train Control systems (ATCS) monitor train speed and train position during a stop, and take action if the train is going too fast or not slowing rapidly enough to assure that it comes to a stop within the required distance. While the stop distance calculation performed by PTC and ATCS systems makes assumptions about the amount of brake power available on the train, it does not accurately reflect the braking power of the train at given point in time. Instead, the PTC/ATCS stop distance calculation is necessarily conservative, as PTC/ATCS systems and block signal systems are designed with the statistical assurance that the train will always have sufficient brake power to stop in less distance than that calculated by the safety system. Accordingly, there is a need in the art for a system that can accurately monitor train brake effectiveness and provide on-board brake monitoring that can accurately determine whether the train can brake within required distances without the need to for frequent periodic train brake inspection and tests.